Metrohm has launched the 855 fluoride analyser, an off-the-shelf robotic fluoride analyser designed to carry out routine high-volume fluoride determination.
Recent examples of samples the system has been used for indicate the possible range of analysis: landfill leachates - 0.1ppm and above; red wine - 0.2ppm; cooking salt - 52ppm; mouthwash - 250ppm; and toothpaste - 1,300ppm.
The sample is treated with an exactly defined volume of total ionic strength adjustment buffer (Tisab) solution and previously this buffer had to be added manually.
An additional Dosino is incorporated in the robotic fluoride analyser to carry out the addition of this buffer.
Due to the flexible programming, the Tisab is added fully automatically before the sample is analysed, with accuracy and precision that is not influenced by the user.
A second Dosino is used for the addition of a known concentration of fluoride standard.
The Dosino is mounted directly on the reagent bottle, saving space on the bench top.
The sensor combination of crystal membrane fluoride ISE and a long-life ISE reference electrode determines the fluoride content of the sample, even at a low sensor immersion depth.
At low ion concentrations and low ionic strengths - and most importantly, for repeated determinations in automated systems - a stable, reproducible reference potential is crucial.
The 6.0750.100 Long-Life reference electrode has a fixed ground-joint diaphragm that provides a constant electrolyte flow.
This is important as the ionic strength and stirring rate have a minor influence on results.
In addition to the fluoride measurement accessories, the 855 robotic analyser comes with an application package containing all the necessary instructions and fluoride methods, including many determination examples in the database.
The methods provided are already included in the Tiamo software as templates.
The data produced is managed an easy-to-use database.
Up to 59 samples per rack can be incorporated.
The 855 adds the standard and auxiliary solutions as well as carrying out the determination.
The 855 rinses the electrodes after every determination and then stores the electrode in the correct medium between runs.
The integration of the ion meter, sample processor and Dosinos ensure little bench-space is taken up.
